Question

calcule as combinações n,4 = 2 ( n, 3​

Answer 1

C(n ,4) = 2. C(n ,3)

n.(n-1).(n-2).(n-3)/4! = 2.n.(n-1).(n-2)/3!

(n-3)/24 = 2/6

(n-3)/24 = 1/3. ==> *(3)

(n-3)/8 = 1

n-3 = 8

n = 11